Four piece set with bits for drilling pilot holes for screw sizes 3 mm, 4 mm, 5 mm and 6 mm. Specially designed steel counterbore and countersink features for precise screw seating and clean finishes. Drill length is adjustable for screws of different lengths by loosening and tightening the set screw. Key benefits - Reliable pilot holes for standard screw sizes 3 to 6 mm, ensuring accurate start and reduced thread stripping. - Steel construction provides durability and long tool life for repetitive use. - Integrated counterbore and countersink capability enables flush screw heads and neat finishes. - Adjustable drilling depth lets you use screws of varying lengths without swapping tools. Specifications and compatibility - Set includes bits for screw diameters: 3 mm, 4 mm, 5 mm, 6 mm. - Material: steel for robust performance and long life. - Adjustment: drill depth controlled by a set screw; loosen to extend depth, tighten to lock in position. Practical use scenarios - Furniture assembly: create precise pilot holes and countersunk seating for a clean, professional look on wooden furniture. - Cabinetry and shelving: ensure uniform screw depths and flush heads when mounting panels and brackets. - DIY projects and repairs: adapt to different screw lengths without changing bits, reducing setup time. Notes - Use appropriate drill speeds and feeds for the material being drilled. - Verify screw diameter and length before selecting the corresponding bit and depth setting.